The normative framework in mediation processes is growing. Mediators are increasingly expected by their mandate-givers to incorporate liberal norms such as inclusivity into their overall strategy. However, in the wake of the terrorist attacks that took place on 11 September 2001, and the policy shifts that accompanied the “Global War on Terror”, mediators find themselves simultaneously pressured to design mediation processes actively excluding armed groups proscribed as terrorists and consequently incorporating this illiberal norm of “exclusivity”, barring proscribed groups’ access to negotiations. This article asks what consequences this development has on the normative agency of mediators, based on if and how they incorporate proscribed armed groups into their mediation strategies. It argues that the dichotomy between liberal and illiberal norms has important consequences on a mediator’s normative agency. First, the dichotomy constrains mediators to a single normative standard, rendering only liberal and illiberal views possible. Second, the assumption that liberal norms are “good” and illiberal norms are “bad” engenders a double dichotomy that greatly constrains a mediator’s normative agency. Third, these constraints on a mediator engender new mediation practices such as outsourcing and risk-sharing in an attempt to salvage normative agency. The article contributes to scholarship on norms, terrorism and mediation through providing a more nuanced view of normative parameters in mediation practice.